Fix MySQL "Access Denied"

Understanding the Error

ERROR 1045 (28000): Access denied for user 'username'@'localhost' (using password: YES)

Fix 1: Reset Root Password

Stop MySQL:

sudo systemctl stop mysql

Start in safe mode (skip grants):

sudo mysqld_safe --skip-grant-tables &

Connect without password:

mysql -u root

Reset password:

FLUSH PRIVILEGES;
ALTER USER 'root'@'localhost' IDENTIFIED BY 'NewStrongPassword';
# For MySQL 5.7 and older:
UPDATE mysql.user SET authentication_string=PASSWORD('NewStrongPassword') WHERE User='root';

Exit and restart normally:

sudo systemctl restart mysql

Fix 2: Check Plugin Authentication

For MySQL 8.0+, some clients don't support caching_sha2_password:

ALTER USER 'username'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';

Fix 3: Verify User Exists and Host

SELECT User, Host FROM mysql.user;

Connect as user@host properly:

# If user exists for localhost only
mysql -u username -p -h localhost

# If user exists for specific IP
mysql -u username -p -h 127.0.0.1

Fix 4: Grant Missing Privileges

GRANT ALL PRIVILEGES ON database.* TO 'username'@'localhost';
FLUSH PRIVILEGES;

Fix 5: Check Password Expiration

SELECT User, password_expired FROM mysql.user;
ALTER USER 'user'@'host' IDENTIFIED BY 'password' PASSWORD EXPIRE NEVER;